I. Field of the Invention
The present invention relates generally to train handling equipment and particularly to systems for indexing a coupled string or trip of cars through a work station, one or more cars at a time during loading or unloading operations. More specifically, the present invention is directed to such a system that is useful in addressing situations of high pit grading where ground clearance is minimal and a unit of compact or low profile is required. The system employs horizontally extending cantilevered car engaging and propelling members to contact the lower portion of car bogey wheel frames.
II. Related Art
Trains, many containing 100 or more cars of identical or a variety of sizes, have long been acknowledged as desirable and efficient carriers of bulk raw materials such as coal, iron ore, limestone, various finely divided dry bulk agricultural products including grains, etc., and liquid or dry chemicals. These cars are typically filled from above and may be emptied using a rotary car dumper in the case of coal or iron ore or, particularly in the case of agricultural products, bottom emptied into stationary freight handling equipment such as chutes, conveyor handlers or the like. The cars may be provided with a number of spaced bottom discharging hopper bins or chutes accessing the main storage volume of the car enclosed by sliding discharge gates. These are designed to be precisely positioned over dedicated recessed receiving facilities situated at fixed stations such as grain or coal bins and conveyors positioned beneath the railroad track. Liquid bulk cargo is typically unloaded by connecting outlets to large hoses with associated pumping equipment and opening bottom drain valves. The cargo then being pumped into tanks or tank trucks located near the tracks.
In the discharge operation, a connected train engine roughly positions one end of a string of cars to be unloaded close to the unloading facility. Because train engines are not well suited for indexing or precisely positioning individual cars or even sets of cars along the track, let alone precisely over individual bins, train positioning devices known as railroad car progressors or indexers have been built and operated at fixed stations. Railroad car indexers of the class of interest include at least one car engaging and propelling member or "dog" for engaging at least one railroad car in a string or trip of cars and moving the string a given distance along the railroad track. The engaging members often situated and operated along an auxiliary indexer track or guideway juxtaposed in parallel relation to the railroad track in the fixed receiving facility. Fluid operated actuators such as hydraulic cylinders or chains and sprockets driven by hydraulic or electric motors supply power for moving the dog and pulling the railroad cars. U.S. Pat. Nos. 4,006,691, issued to Kacir et al, and 4,354,792, issued to Cornish, show train positioners that approach the train from alongside the track and including an engaging member arm which engages a car coupler from above.
Other types of indexing or positioning devices utilize dogs in the form of heavy vertically pivoting car-engaging arm members which are designed to engage and advance either the railway bogey wheel truck frame or an axle. The dogs are smaller than car coupler engaging arms and are carried by dog carriages which ride on a dog carriage indexer track situated either between the rails of the railroad track to engage the axle or next to the railroad track to engage the bogey truck frame. Bogey frame-engaging dog systems may be further divided into two types. One type includes "low dogs" which are dogs that engage the lower portion of the truck frame below the axle; and the other employs "high dogs" which engage the frame at or above the height of the axles. One such system using high dogs is described in U.S. Pat. No. 5,709,153 to Brandt, the inventor of the present invention, is assigned to the same assignee as the present invention.
Most of these indexing systems require an amount of space below the track level between or alongside the track to accommodate elements of the systems required to operate the vertically pivoting dogs which pop up to engage the bogey frames or axles of cars and are dropped for storage. Unfortunately, many facilities for conducting unloading operations have been constructed with very little vertical room for the installation of auxiliary equipment between or alongside of the rails due to high pit gradings and existing slab access pit covers or the like. This leaves very little vertical space to accommodate train indexing equipment including operating systems and dogs alike. This precludes the installation of most types of conventional vertically operating high or low dog systems. Accordingly, there exists a need for a vertically compact train indexing system that can be effectively installed and operated in low clearance environments.
Accordingly, it is primary object of the present invention to provide a low clearance train positioning system that can be used in situations of zero track clearance.
It is a further object of the present invention to provide a low clearance train positioning system that uses horizontally operating dogs to engage the bogey frame of a car from the side.
A still further object of the present invention is to provide a low clearance train positioning system that is a reversing system utilizing spaced opposed dogs.
Another object of the present invention is to provide a low clearance train positioning system that includes a system for retracting and locking down the dogs.
Yet another object of the present invention is to provide a low clearance train positioning system utilizing horizontally operating low dogs which pivot in a low horizontal plane to engage the bogey frame of a car from the side.
Still another object of the present invention is to provide such a low clearance train positioning system utilizing horizontally pivoting arm-like low dogs which includes a system for stabilizing empty cars.
Yet still another object of the present invention is to provide a low clearance train positioning system capable of being installed without disturbing existing track-high, track side concrete pads.
Other objects and advantages associated with the present invention will reveal themselves or become apparent to those skilled in the art upon familiarization with the specification, drawings and claims contained herein.